Transcript Electrical Circuits 1 (from CPO Physics)

Foundations of Physical
Science
Workshop: Electric Circuits
Electric Circuits
CPO Science
Key Questions
 What “flow of understanding”
provides the necessary
foundation for an understanding
of electricity?
 What kinds of electric circuits
can you build?
 How does electricity behave?
Light the Bulb!
What needs to
happen to get
the bulb to
light?
Parts of our Circuits Kit
 Wooden Board
 Wires of various lengths
 On/Off switches
 Bulbs and holder
 Resistors – fixed and variable
Build a simple Circuit

Place the bulb in a socket
 Use one D cell
 Make the bulb light!
 Add a switch to conserve D cell energy
 Use your finger to trace the path of
electricity from one terminal of the D
cell to the other terminal
Parts of a Circuit
 Wire
 Bulb
 Battery
 Switch
Symbols used for
Diagramming
Let’s build on this…
 Add a second D cell to your circuit, right
next to the first. Be sure to match up
positive terminal with negative terminal
 Do you notice any difference?
 Add a second light bulb to the circuit,
keeping only one pathway for electricity
to follow
 What do you observe now?
Series Circuit
Another way to light two
bulbs
 Keep two D cells in the circuit
 Wire up the 2 light bulbs so that
there are two branches or pathways
for electricity to follow
 What differences do you observe?
Parallel Circuit
Can you explain why
the bulbs in a
parallel circuit are
brighter?
Water Analogy
Resistance and Current
Inverse Relationship
Voltage
The amount of
potential energy
that each unit of
charge has
Review
 V = voltage, measured in volts
 I = current, measured in
amperes, or amp
 R = resistance, measured in
Ohms, symbol W
Using the Multimeter to measure
Voltage
 Battery by itself

Battery in a circuit
Using the Multimeter to
measure Current

Current in a
circuit
 Multimeter
completes the
circuit
Analyze Circuits
1 bulb
Total voltage
available
Voltage across
each bulb
Total current at
terminal
Current through
each bulb
2 bulbs in 2 bulbs in
series
parallel
Why are parallel bulbs brighter?
1 bulb
Total voltage
available
Voltage across
each bulb
Total current at
terminal
Current through
each bulb
2.8 V
2 bulbs in 2 bulbs in
series
parallel
2.8 V
2.8 V
2.8 V
1.4 V
2.8 V
.12 A
.10 A
0.24 A
.12 A
.10 A
0.12 A